Method and apparatus for interference reporting in a N-MIMO communication system

ABSTRACT

Systems and methodologies are described herein that facilitate interference measurement and reporting in a network multiple-in-multiple-out (N-MIMO) communication system. As described herein, a network device can measure and report interference corresponding to network nodes outside a designated set of nodes that can cooperatively serve the device. Respective interference reports can additionally identify dominant interfering nodes, correlation between transmit antennas of respective nodes, or the like. Subsequently, respective interference reports can be combined with per-node channel information to manage coordination and scheduling across respective network nodes. As further described herein, interference from a network node can be measured by observing reference and/or synchronization signals from the network node. To aid such observation, respective non-interfering network nodes can define null pilot intervals in which transmission is silenced or otherwise reduced. As additionally described herein, loading information broadcasted by respective interfering network nodes can be identified and utilized in connection with interference calculation.

RELATED APPLICATION

The present application for patent is a Continuation of patentapplication Ser. No. 12/580,139 entitled “METHOD AND APPARATUS FORINTERFERENCE REPORTING IN A N-MIMO COMMUNICATION SYSTEM” filed Oct. 15,2009, pending, which claims priority to U.S. Provisional ApplicationSer. No. 61/108,278, filed Oct. 24, 2008, and entitled “INTERFERENCEREPORTING FOR N-MIMO SYSTEMS,” and U.S. Provisional Application Ser. No.61/162,613, filed Mar. 23, 2009, and entitled “INTERFERENCE REPORTINGFOR N-MIMO SYSTEMS.” The foregoing applications are incorporated hereinby reference in their entireties.

BACKGROUND

I. Field

The present disclosure relates generally to wireless communications, andmore specifically to techniques for supporting coordinated communicationacross network nodes in a wireless communication environment.

II. Background

Wireless communication systems are widely deployed to provide variouscommunication services; for instance, voice, video, packet data,broadcast, and messaging services can be provided via such wirelesscommunication systems. These systems can be multiple-access systems thatare capable of supporting communication for multiple terminals bysharing available system resources. Examples of such multiple-accesssystems include Code Division Multiple Access (CDMA) systems, TimeDivision Multiple Access (TDMA) systems, Frequency Division MultipleAccess (FDMA) systems, and Orthogonal Frequency Division Multiple Access(OFDMA) systems.

As the demand for high-rate and multimedia data services rapidly grows,there has been an effort toward implementation of efficient and robustcommunication systems with enhanced performance. For example, in recentyears, users have started to replace fixed line communications withmobile communications and have increasingly demanded great voicequality, reliable service, and low prices. In addition to mobiletelephone networks currently in place, a new class of small basestations has emerged, which can be installed in the home of a user andprovide indoor wireless coverage to mobile units using existingbroadband Internet connections. Such personal miniature base stationsare generally known as access point base stations, or, alternatively,Home Node B (HNB) or Femto cells. Typically, such miniature basestations are connected to the Internet and the network of a mobileoperator via a Digital Subscriber Line (DSL) router, cable modem, or thelike.

Wireless communication systems can be configured to include a series ofwireless access points, which can provide coverage for respectivelocations within the system. Such a network structure is generallyreferred to as a cellular network structure, and access points and/orthe locations they respectively serve in the network are generallyreferred to as cells.

Further, in a multiple-in-multiple-out (MIMO) communication system,multiple sources and/or destinations (e.g., corresponding to respectiveantennas) can be utilized for the transmission and reception of data,control signaling, and/or other information between devices in thecommunication system. The use of multiple sources and/or destinationsfor respective transmissions in connection with a MIMO communicationsystem has been shown to yield higher data rates, improved signalquality, and other such benefits over single-input and/or single-outputcommunication systems in some cases. One example of a MIMO communicationsystem is a Network MIMO (N-MIMO) or Coordinated Multipoint (CoMP)system, in which a plurality of network nodes can cooperate to exchangeinformation with one or more receiving devices, such as user equipmentunits (UEs) or the like.

Coordination between network nodes in a N-MIMO communication system canbe conducted according to one or more coordination strategies based onvarious network parameters, parameters relating to a user device forwhich coordination is to be conducted, and/or other suitable factors.Accordingly, it would be desirable to implement techniques forgenerating and processing feedback reports corresponding to interferenceand/or other network parameters in order to improve system performancegains associated with multi-node coordination in a N-MIMO communicationsystem.

SUMMARY

The following presents a simplified summary of various aspects of theclaimed subject matter in order to provide a basic understanding of suchaspects. This summary is not an extensive overview of all contemplatedaspects, and is intended to neither identify key or critical elementsnor delineate the scope of such aspects. Its sole purpose is to presentsome concepts of the disclosed aspects in a simplified form as a preludeto the more detailed description that is presented later.

According to an aspect, a method is described herein. The method cancomprise identifying a set of network cells operable to conductcommunication with inter-site coordination; measuring an amount ofreceived power from respective network cells not associated with theidentified set of network cells; and reporting a measured amount ofreceived power to one or more network cells in the identified set ofnetwork cells.

A second aspect described herein relates to a wireless communicationsapparatus, which can comprise a memory that stores data relating to aset of serving network nodes operable to conduct communication withinter-node coordination. The wireless communications apparatus canfurther comprise a processor configured to measure an amount of receivedpower from respective network nodes not associated with the set ofserving network nodes and to report a measured amount of received powerto one or more serving network nodes.

A third aspect relates to an apparatus, which can comprise means foridentifying a set of associated network nodes operable to perform atleast one of uplink communication or downlink communication usinginter-node coordination and means for reporting an amount of receivedpower corresponding to respective network nodes not associated with theset of associated network nodes.

A fourth aspect relates to a computer program product, which cancomprise a computer-readable medium that comprises code for causing acomputer to identify a set of associated network nodes operable toperform at least one of uplink communication or downlink communicationusing inter-node coordination and code for causing a computer to reportan amount of received power corresponding to respective network nodesnot associated with the set of associated network nodes.

A fifth aspect described herein relates to a method, which can comprisedefining an interference reporting schedule for one or more associateduser equipment units (UEs); scheduling respective null pilot intervalswithin the interference reporting schedule; and conducting limitedtransmission upon occurrence of a scheduled null pilot interval withinthe interference reporting schedule.

A sixth aspect described herein relates to a wireless communicationsapparatus, which can comprise a memory that stores data relating to oneor more user devices and an interference reporting schedule associatedwith the one or more user devices. The wireless communications apparatuscan further comprise a processor configured to define respective nullpilot intervals within the interference reporting schedule such thatlimiting is performed for communication occurring substantiallysimultaneously with the respective null pilot intervals.

A seventh aspect relates to an apparatus, which can comprise means fordefining an interference reporting schedule for respective associateduser devices, wherein the interference reporting schedule includes oneor more null pilots and means for performing at least one of transmitsilencing or transmit power backoff upon occurrence of respective nullpilots in the interference reporting schedule.

An eighth aspect relates to a computer program product, which cancomprise a computer-readable medium that comprises code for causing acomputer to define an interference reporting schedule for respectiveassociated UEs, wherein the interference reporting schedule includes oneor more null pilots, and code for causing a computer to conduct at leastone of transmit silencing or transmit power backoff upon occurrence ofrespective null pilots in the interference reporting schedule.

To the accomplishment of the foregoing and related ends, one or moreaspects of the claimed subject matter comprise the features hereinafterfully described and particularly pointed out in the claims. Thefollowing description and the annexed drawings set forth in detailcertain illustrative aspects of the claimed subject matter. Theseaspects are indicative, however, of but a few of the various ways inwhich the principles of the claimed subject matter can be employed.Further, the disclosed aspects are intended to include all such aspectsand their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system for feedback generation andreporting in a N-MIMO communication system in accordance with variousaspects.

FIG. 2 is a block diagram of a system for performing and reportingmeasurements relating to interference observed in a distributed wirelesscommunication environment in accordance with various aspects.

FIG. 3 is a block diagram of a system that facilitates measurement andreporting of interference across a set of resources utilized by anassociated wireless communication system in accordance with variousaspects.

FIGS. 4-5 are block diagrams of respective systems that facilitateobservation and measurement of interference by a user device in awireless communication environment in accordance with various aspects.

FIGS. 6-8 is are flow diagrams of respective methodologies forinterference measurement and reporting in a N-MIMO communication system.

FIG. 9 is a flow diagram of a methodology for managing an interferencereporting schedule in a N-MIMO communication system.

FIGS. 10-11 are block diagrams of respective apparatuses that facilitatereporting and processing of interference information in a wirelesscommunication system.

FIGS. 12-13 are block diagrams of respective example systems thatfacilitate coordinated multipoint communication in accordance withvarious aspects described herein.

FIG. 14 illustrates an example wireless communication system inaccordance with various aspects set forth herein.

FIG. 15 is a block diagram illustrating an example wirelesscommunication system in which various aspects described herein canfunction.

FIG. 16 illustrates an example communication system that enablesdeployment of access point base stations within a network environment.

DETAILED DESCRIPTION

Various aspects of the claimed subject matter are now described withreference to the drawings, wherein like reference numerals are used torefer to like elements throughout. In the following description, forpurposes of explanation, numerous specific details are set forth inorder to provide a thorough understanding of one or more aspects. It maybe evident, however, that such aspect(s) may be practiced without thesespecific details. In other instances, well-known structures and devicesare shown in block diagram form in order to facilitate describing one ormore aspects.

As used in this application, the terms “component,” “module,” “system,”and the like are intended to refer to a computer-related entity, eitherhardware, firmware, a combination of hardware and software, software, orsoftware in execution. For example, a component can be, but is notlimited to being, a process running on a processor, an integratedcircuit, an object, an executable, a thread of execution, a program,and/or a computer. By way of illustration, both an application runningon a computing device and the computing device can be a component. Oneor more components can reside within a process and/or thread ofexecution and a component can be localized on one computer and/ordistributed between two or more computers. In addition, these componentscan execute from various computer readable media having various datastructures stored thereon. The components can communicate by way oflocal and/or remote processes such as in accordance with a signal havingone or more data packets (e.g., data from one component interacting withanother component in a local system, distributed system, and/or across anetwork such as the Internet with other systems by way of the signal).

Furthermore, various aspects are described herein in connection with awireless terminal and/or a base station. A wireless terminal can referto a device providing voice and/or data connectivity to a user. Awireless terminal can be connected to a computing device such as alaptop computer or desktop computer, or it can be a self containeddevice such as a personal digital assistant (PDA). A wireless terminalcan also be called a system, a subscriber unit, a subscriber station,mobile station, mobile, remote station, access point, remote terminal,access terminal, user terminal, user agent, user device, or userequipment (UE). A wireless terminal can be a subscriber station,wireless device, cellular telephone, PCS telephone, cordless telephone,a Session Initiation Protocol (SIP) phone, a wireless local loop (WLL)station, a personal digital assistant (PDA), a handheld device havingwireless connection capability, or other processing device connected toa wireless modem. A base station (e.g., access point or Node B) canrefer to a device in an access network that communicates over theair-interface, through one or more sectors, with wireless terminals. Thebase station can act as a router between the wireless terminal and therest of the access network, which can include an Internet Protocol (IP)network, by converting received air-interface frames to IP packets. Thebase station also coordinates management of attributes for the airinterface.

Moreover, various functions described herein can be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions can be stored on or transmitted over as oneor more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage media can be anyavailable media that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and blu-ray disc (BD), where disks usuallyreproduce data magnetically and discs reproduce data optically withlasers. Combinations of the above should also be included within thescope of computer-readable media.

Various techniques described herein can be used for various wirelesscommunication systems, such as Code Division Multiple Access (CDMA)systems, Time Division Multiple Access (TDMA) systems, FrequencyDivision Multiple Access (FDMA) systems, Orthogonal Frequency DivisionMultiple Access (OFDMA) systems, Single Carrier FDMA (SC-FDMA) systems,and other such systems. The terms “system” and “network” are often usedherein interchangeably. A CDMA system can implement a radio technologysuch as Universal Terrestrial Radio Access (UTRA), CDMA2000, etc. UTRAincludes Wideband-CDMA (W-CDMA) and other variants of CDMA.Additionally, CDMA2000 covers the IS-2000, IS-95 and IS-856 standards. ATDMA system can implement a radio technology such as Global System forMobile Communications (GSM). An OFDMA system can implement a radiotechnology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB),IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM®, etc.UTRA and E-UTRA are part of Universal Mobile Telecommunication System(UMTS). 3GPP Long Term Evolution (LTE) is an upcoming release that usesE-UTRA, which employs OFDMA on the downlink and SC-FDMA on the uplink.UTRA, E-UTRA, UMTS, LTE and GSM are described in documents from anorganization named “3rd Generation Partnership Project” (3GPP). Further,CDMA2000 and UMB are described in documents from an organization named“3rd Generation Partnership Project 2” (3GPP2).

Various aspects will be presented in terms of systems that can include anumber of devices, components, modules, and the like. It is to beunderstood and appreciated that the various systems can includeadditional devices, components, modules, etc. and/or can not include allof the devices, components, modules etc. discussed in connection withthe figures. A combination of these approaches can also be used.

Referring now to the drawings, FIG. 1 illustrates a system 100 forfeedback generation and reporting in a network multi-in-multi-out(Network MIMO or N-MIMO) communication system in accordance with variousaspects. As illustrated in FIG. 1, system 100 can include a UE 110,which can communicate with one or more serving cells 120 and/or othersuitable network nodes associated with a “serving set” 102 for UE 110.For example, UE 110 can conduct one or more uplink (UL, also referred toas reverse link (RL)) communications to respective serving cells 120,and serving cell(s) 120 can conduct one or more downlink (DL, alsoreferred to as forward link (FL)) communications to UE 110.

In one example, serving set 102 can include all network nodes that canpotentially be utilized to serve UE 110. While all such network cellsare labeled as “serving cells” 120 in system 100, it should beappreciated that UE 110 can communication with all serving cells 120, asubset of less than all serving cells 120, or no serving cells 120 atany given time. In addition, system 100 can include one or morenon-serving cells 130 that do not provide service for UE 110. In oneexample, respective serving cells 120 and/or non-serving cells 130 cancorrespond to and/or provide communication coverage for any suitablecoverage area(s), such as an area associated with a macro cell, a femtocell (e.g., an access point base station or Home Node B (HNB)), and/orany other suitable coverage area.

In accordance with one aspect, system 100 can utilize one or moreN-MIMO, coordinated multipoint (CoMP), and/or other techniques by whicha single UE 110 can communicate with a plurality of disparate servingcells 120. In one example, N-MIMO communication can be conducted on theuplink and/or the downlink using any suitable strategy or combination ofstrategies for coordination between serving cells 120. Such strategiescan include, for example, silencing, frequency reuse, coordinatedbeamforming (CBF), joint transmission (JT), and/or any other suitablecooperation strategies as described herein and/or as generally known inthe art.

In accordance with another aspect, a serving cell 120 can receivevarious parameters relating to a given UE 110, system 100, other servingcells 120, or the like from a UE 110. Such feedback can be processed bya feedback processing module 122 and/or other appropriate mechanisms atserving cell 120, based on which a coordination strategy selector 124can determine a coordination strategy to be utilized across servingcells 120 in serving set 102 for communication with UE 110.

In traditional wireless communication systems that utilize a singleserving cell for a given UE, a UE can report feedback including aChannel Quality Indicator (CQI). CQI feedback as provided by a UE can beexpressed, for example, in terms of a ratio of the signal power from theserving cell associated with the UE to the interfering power from allother cells. Based on this information, a cell in a single serving cellsystem can be enabled to ascertain an effective indication of the ratethat can be achieved for the corresponding UE.

In contrast, however, it can be appreciated that the set of servingcells 120 that contribute to signals observed by a given UE 110 (e.g.,as opposed to interference) can in some cases not be predetermined. Forexample, a UE 110 can be served by a single cell or multiple cells as afunction of various UE-specific and/or network parameters. In addition,if a serving set 102 is predetermined for a given UE 110, it can furtherbe appreciated that a coordination strategy employed by respectiveserving cells 120 in the serving set 102 can in some cases change overtime (e.g., by utilizing different beam directions at different timesand/or in any other manner). Accordingly, if the UE 110 is not madeaware in advance of the composition of serving cells 120 in serving set102 and/or a coordination strategy to be utilized between such servingcells 120, UE 110 may in some cases be unable to compute its achievablerate. It can be appreciated that this, in turn, can cause respectiveserving cells 120 for UE 110 to experience difficulties in performingcoordination strategy selection. As a result, it can further beappreciated that CQI can in some cases be substantially dependent onscheduling and/or coordination decisions made by respective servingcells 120, thereby rendering a traditional CQI metric insufficient insome cases for coordination strategy selection in a N-MIMOcommunication.

In accordance with one aspect, a UE 110 can mitigate at least theshortcomings of traditional CQI reporting as noted above by measuringand reporting (e.g., via an interference measurement module 112 and aninterference reporting module 114, respectively) a sum or totalinterference observed from all non-serving cells 130 (e.g., all networkcells not in an associated serving set 102). Thus, for example, if UE110 can potentially be served by one or both of a cell A and a cell B,interference reporting module 114 and/or another suitable mechanism canbe utilized by UE 110 to report the received power from all cellsexcluding cells A and B (e.g., as measured by interference measurementmodule 112 and/or other suitable mechanisms).

In accordance with another aspect, a serving cell 120 that receives acombined interference report from a UE 110 as provided above can processthe feedback via a feedback processing module 122 and/or any othersuitable means, based on which a coordination strategy selector 124 canfacilitate selection and scheduling of a coordination scheme to beutilized across serving cells 120 for UE 110. For example, based oninterference information and/or other suitable information provided byUE 110 relating to achievable channel quality under various coordinationschemes, coordination strategy selector 124 can select an appropriatestrategy for inter-node cooperation (e.g., inter-site packet sharing,coordinated transmit interference nulling, etc.) and subsequentlyschedule one or more serving cells 120 for communication with UE 110pursuant to the selected cooperation strategy.

In accordance with a further aspect, UE 110 can additionally oralternatively include an optional per-node channel analysis module 116and channel reporting module 118, which can be utilized to respectivelymeasure and report information corresponding to channel conditionscorresponding to respective serving cells 120. Thus, for example,channel reporting module 118 can provide feedback to respective servingcells 120 corresponding to the observed strength of downlink channelscorresponding to the respective serving cells 120 and/or any otherindicator of the quality of downlink channels corresponding to servingcells 120.

In one example, per-node channel information provided by channelreporting module 118 in the above manner can be utilized by a feedbackprocessing module 122 and/or coordination strategy selector 124 atrespective serving cells to facilitate further refinement tocoordination strategy selection and/or scheduling. For example,coordination strategy selector 124 can identify observed downlinkchannel strength corresponding to respective serving cells 120 andutilize such information to approximate the potential interferenceimpact of the respective serving cells 120 on communication with anassociated UE 110. Accordingly, coordination strategy selector 124 canutilize reported interference and channel information to identify acoordination scheme and a combination of serving cells 120 to beutilized therewith in order to minimize interference observed at UE 110,to maximize overall system throughput, and/or to achieve otherappropriate benefits within system 100. By way of a specificillustrative example, upon selecting coordinated beamforming as acooperation scheme between serving cells 120, coordination strategyselector 124 can determine a channel quality that would result frominstructing respective serving cells to form beams away from anassociated UE 110 and make scheduling decisions accordingly. In anotherexample, coordination strategy selector 124 can utilize feedbackprovided by a UE 110 to select a packet size to be utilized fortransmission to UE 110 on a given set of resources.

In another example, coordination strategy selector 124 can utilizefeedback obtained from a UE 110 to facilitate clustering and/orscheduling of nodes to be utilized for communication with UE 110. Forexample, based on channel conditions, buffer state, and/or otherparameters relating to a UE 110, respective serving cells 120 in aserving set 102 for UE 110 can be clustered or scheduled into acooperation strategy for serving UE 110. Further, clustering asperformed by coordination strategy selector 124 can be made dynamic suchthat identities of respective serving cells 120 and/or a number ofserving cells 120 associated with UE 110 can be modified in real-timebased on changing network conditions. Additionally or alternatively, themanner in which respective clustered cells cooperate with respect to agiven UE 110 can be dynamically assigned based on continuously monitorednetwork conditions. For example, a serving cell 120 associated with a UE110 at a given time can be instructed to actively transmit to UE 110, toform beams away from UE 110, to back off a present transmit power (e.g.,based on an explicit power backoff request or an implicit request basedon a desired amount of interference reduction), and/or to cooperate withrespect to UE 110 in any other suitable manner.

Turning now to FIG. 2, a system 200 for performing and reportingmeasurements relating to interference observed in a distributed wirelesscommunication environment in accordance with various aspects isillustrated. In one example, system 200 can include an interferencemeasurement module 112, which can be employed by a user device (e.g., UE110) and/or another suitable network device to perform respectiveinterference measurements. Upon generation of interference informationby interference measurement module 112, the information can subsequentlybe reported (e.g., to respective serving cells 120) by an interferencereporting module 114.

In accordance with one aspect, interference measurement module 112 canutilize a primary interferer identification module 212 and/or othersuitable means to identify one or more network entities from whichsubstantial interference is observed. Upon identification, informationrelating to observed primary interferers can be provided to interferencereporting module 114 for inclusion in a related interference report.

Additionally or alternatively, interference measurement module 112 caninclude a correlation analyzer 214, which can identify and facilitatereporting of correlation of observed interference. For example, ifprimary interferer identification module 212 identifies only a singleinterferer and the interferer is determined to have multiple transmitantennas, correlation analyzer 214 can be utilized to compute thecorrelation between the transmit antennas of the interferer. In anotherexample, if a device associated with interference measurement module 112has multiple receive antennas, the device can in some cases beconfigured to null some or all interference observed from a singleinterferer. Such receiver interference nulling can be performed, forexample, based on a receiver implementation utilized by the deviceassociated with interference measurement module (e.g., minimum meansquare error (MMSE), etc.). In accordance with one aspect, interferencereporting module 114 can report information relating to analyzedcorrelations either explicitly or implicitly (e.g., in the form of arate that can be achieved subsequent to nulling, as determined by anoptional rate projection module 222).

In another example, in the event that a given network cell hascorrelated antennas (e.g., antennas spaced on the order of half of awavelength) and a channel associated with the cell changes substantiallyfrequently but does not exhibit a significant angular spread,correlation analyzer 214 can measure a long-term coherence matrixcorresponding to the channel and facilitate reporting of the coherencematrix to the corresponding cell via interference reporting module 114.Accordingly, if the coherence matrix is, for example, a low-rank matrix,it can be appreciated that a network cell and/or other entity thatreceives the matrix can facilitate direction of beams to and/or from adevice associated with system 200 even in the absence of completechannel information.

In accordance with one aspect, interference estimates made byinterference measurement module 112 and reported by interferencereporting module 114 can be provided to respective network cells in anexplicit or implicit fashion. For example, an implicit interferencereport can be constructed by an optional rate projection module 222and/or other suitable means by, for example, estimating a rate that canbe achieved when only a given serving cell is transmitting. Further,interference reporting module 114 can provide feedback to respectivenetwork cells over a dedicated physical layer channel, using an existingphysical layer (e.g., Layer 1 or L1) signaling channel (e.g., a PhysicalUplink Control Channel (PUCCH)), via Layer 3 (L3) signaling, and/or inany other suitable manner(s).

In accordance with another aspect, interference estimates reported byinterference reporting module 114 can correspond to an entire frequencybandwidth designated for an associated communication system, oralternatively interference feedback can be configured to vary on aper-resource unit basis (e.g., from subframe to subframe, sub-band tosub-band, etc.). This is illustrated by diagram 300 in FIG. 3, wherein aset of interference estimates 312 generated by interference measurementmodule 112 and/or interference reports 322 communicated by interferencereporting module 114 can be structured to correspond to a set of Kresource units (e.g., subframes, sub-bands, resource blocks, etc.).

In accordance with a further aspect, interference from respectivenon-serving cells 130 can be computed by a UE 110 in various manners.Respective examples of techniques that can be conducted by a UE 110 forinterference observation and measurement are illustrated by systems400-500 in FIGS. 4-5. With specific reference first to system 400 inFIG. 4, a serving cell 120 associated with a UE 110 can utilize a nullpilot management module 412 and/or any other suitable means to define“null pilot” periods in an associated communication timeline. In oneexample, null pilot management module 412 can facilitate transmissionsilencing, transmit power backoff, and/or any other suitable operationsat respectively predefined null pilot intervals in time in order toenable an associated UE 110 to observe interfering signals fromrespective non-serving cells 130 at the predefined null pilot periodswith little or no additional signal energy being radiated from anassociated serving cell 120.

Additionally or alternatively, an interference measurement module 112and/or other suitable means at a UE 110 can analyze signal strengths ofpreambles, reference signals, synchronization signals (e.g., a primarysynchronization signal (PSS) and/or secondary synchronization signal(SSS)), and/or other signals broadcasted by respective non-serving cells130 to compute interference associated with the non-serving cells 130.Thus, as shown by system 500 in FIG. 5, a synchronization signalgenerator 522 and/or other suitable means at a non-serving cell 130 canbe utilized to broadcast one or more reference and/or synchronizationsignals, based on which UE 110 can estimate interference associated withthe non-serving cell 130.

In accordance with another aspect illustrated by system 500,interference measurement module 112 can leverage loading informationprovided by respective non-serving cells 130 to refine interferenceestimates corresponding to the non-serving cells 130. In particular, anon-serving cell 130 can include a loading indicator module 524, whichcan broadcast an indication of the loading of the non-serving cell 130on a preamble channel (e.g., a Low Reuse Preamble (LRP) channel) and/oranother suitable channel, based on which a cell loading analyzer 512and/or other suitable means at UE 110 can compute a loading-basedinterference estimate for the non-serving cell 130. In another example,such a loading indication can be provided in a master information block(MIB). provided in one or more associated system information blocks(SIBS), implicitly provided based on the relative phase between a PSSand SSS and/or consecutive PSS and/or SSS instances, and/or provided inany other suitable manner.

In one example, a loading indicator provided by loading indicator module524 can be a binary indicator that is reflective of the presence oftraffic to be served by the associated cell 130. By way of specificexample, upon determining that a loading indicator associated with acell 130 is set, cell loading analyzer 512 can facilitate computation ofan interference estimate under the assumption that the cell 130 istransmitting at its nominal power across the entire bandwidth.Alternatively, if the loading indicator is not set, cell loadinganalyzer 512 can facilitate interference computation under an assumptionthat no transmissions are being conducted from the cell 130. In analternative example, a multi-bit loading indicator can be utilized thatcan convey, for example, an average percentage of bandwidth and/or powerusage by an associated cell 130 and/or any other suitable indicator(s).In one example, such a loading indicator can be utilized by cell loadinganalyzer 512 to compute an effective interference contribution from thecorresponding cell 130.

Referring now to FIGS. 6-9, methodologies that can be performed inaccordance with various aspects set forth herein are illustrated. While,for purposes of simplicity of explanation, the methodologies are shownand described as a series of acts, it is to be understood andappreciated that the methodologies are not limited by the order of acts,as some acts can, in accordance with one or more aspects, occur indifferent orders and/or concurrently with other acts from that shown anddescribed herein. For example, those skilled in the art will understandand appreciate that a methodology could alternatively be represented asa series of interrelated states or events, such as in a state diagram.Moreover, not all illustrated acts may be required to implement amethodology in accordance with one or more aspects.

With reference to FIG. 6, illustrated is a methodology 600 forinterference measurement and reporting in a N-MIMO communication system.It is to be appreciated that methodology 600 can be performed by, forexample, a user device (e.g., UE 110) and/or any other appropriatenetwork device. Methodology 600 can begin at block 602, wherein a set(e.g., serving set 102) of network cells operable to perform inter-sitecoordination for uplink and/or downlink communication (e.g., servingcell(s) 120) are identified. Next, at block 604, an amount of receivedpower from respective network cells not associated with the set ofnetwork cells identified at block 602 (e.g., non-serving cell(s) 130) ismeasured (e.g., via an interference measurement module 112). At block606, a measured amount of received power as measured at block 604 canthen be reported (e.g., using an interference reporting module 114) toone or more network cells in the set identified at block 602.

Upon completing the acts described at block 606, methodology 600 canconclude. Alternatively, methodology can optionally proceed to blocks608 and 610 prior to concluding. At block 608, channel qualityassociated with respective channels corresponding to network cells inthe set identified at block 602 is observed (e.g., by a per-node channelanalysis module 116). At block 610, one or more reports of channelquality as observed at block 608 are provided (e.g., using a channelreporting module 118) to respective corresponding network cells.

Turning next to FIG. 7, a flow diagram of a methodology 700 forleveraging correlation data for interference reporting in a wirelesscommunication system is illustrated. Methodology 700 can be performedby, for example, a UE and/or any other appropriate network entity.Methodology 700 begins at block 702, wherein one or more primaryinterfering network entities (e.g., network cells 120 and/or 130) havingmultiple transmit antennas are identified (e.g., using a primaryinterferer identification module 212). At block 704, correlation betweenrespective transmit antennas of the one or more primary interferingnetwork entities identified at block 704 is computed (e.g., via acorrelation analyzer 214). Methodology 700 can then conclude at block706, wherein the correlation computed at block 704 is reported to atleast one serving network node.

FIG. 8 illustrates a methodology 800 for leveraging node loading datafor interference reporting in a wireless communication system.Methodology 800 can be performed by, for example, a mobile stationand/or any other appropriate network entity. Methodology 800 begins atblock 802, wherein one or more interfering network nodes are identified.Next, at block 804, loading of respective interfering network nodesidentified at block 802 is determined (e.g., using a cell loadinganalyzer 512) based at least in part on loading indicators provided bythe interfering network nodes (e.g., via a loading indicator module524). Methodology 800 can then conclude at block 806, whereininterference caused by the respective interfering network nodes isestimated as a function of their loading as determined at block 804.

With reference next to FIG. 9, illustrated is a methodology 900 formanaging an interference reporting schedule in a N-MIMO communicationsystem. It is to be appreciated that methodology 900 can be performedby, for example, a network node (e.g., a serving cell 120) and/or anyother appropriate network entity. Methodology 900 can begin at block902, wherein an interference reporting schedule for one or more relatedUEs (e.g., UEs 110) is defined. Next, at block 904, respective nullpilot intervals are scheduled (e.g., by a null pilot management module412) within the interference reporting schedule defined at block 902.Methodology 900 can then conclude at block 906, wherein transmission byan entity performing methodology 900 is limited and/or silenced uponoccurrence of respective null pilot intervals as scheduled at block 904.

Referring now to FIGS. 10-11, respective apparatuses 1000-1100 thatfacilitate reporting and processing of interference information in awireless communication system are illustrated. It is to be appreciatedthat apparatuses 1000-1100 are represented as including functionalblocks, which can be functional blocks that represent functionsimplemented by a processor, software, or combination thereof (e.g.,firmware).

Turning first to FIG. 10, an apparatus 1000 that facilitates reportingand processing of interference information in a wireless communicationsystem is illustrated. Apparatus 1000 can be implemented by a userstation (e.g., UE 110) and/or another suitable network entity and caninclude a module 1002 for identifying respective associated networknodes operable to perform uplink and/or downlink inter-node coordinationand a module 1004 for reporting an amount of received power fromrespective non-identified network nodes

FIG. 11 illustrates another apparatus 1100 that facilitates reportingand processing of interference information in a wireless communicationsystem. Apparatus 1100 can be implemented by a network node designatedas a serving network node for a given user (e.g., a serving cell 120 fora UE 110) and/or another suitable network entity and can include amodule 1102 for defining an interference reporting schedule forrespective associated user devices that includes one or more null pilotsand a module 1104 for performing at least one of transmit silencing orpower backoff during respective null pilots in the interferencereporting schedule.

Referring now to FIG. 12, an example system 1200 that facilitatescoordinated multipoint communication in accordance with various aspectsis illustrated. As illustrated in FIG. 12, system 1200 can include oneor more network cells 1210 and/or other network nodes, which cancommunicate with respective UEs 1220 as generally described herein. Inaccordance with one aspect, respective cells 1210 in system 1200 cancoordinate pursuant to one or more cooperation strategies in order toincrease data rates associated with communication with a given UE 1220and/or to reduce interference caused to other cells 1210 and/or UEs 1220in system 1200. In one example, respective cells 1210 in system 1200 canbe operable to utilize various cooperation techniques for uplink and/ordownlink communication with one or more UEs 1220, such as coordinatedsilencing (CS), joint transmission (JT) via inter-eNodeB (inter-cell)packet sharing, coordinated beamforming (CBF), and/or any other suitablecell cooperation technique(s) as generally known in the art.

In another example, various operational aspects of system 1200, such asrespective cell cooperation techniques to be utilized for communication,cells 1210 to be utilized for such cooperation techniques, andrespective UEs 1220 to be served via cooperative communication, can becontrolled by a utility computation module 1212 and/or other suitablemechanisms of respective cells 1210. Further, determinations made byutility computation module 1212 can be supported at least in part bymarginal utility calculations performed by one or more cells 1210 (e.g.,via a utility computation module 1214) and/or any other suitable metric.

In general, a cooperation strategy selector 1214 can be utilized by acell 1210 to compute and/or make scheduling decisions relating to nodeclustering, scheduling, forms of cooperative transmission to beutilized, and so on. A cooperation strategy can be selected bycooperation type selector 1214 based on factors such as UE mobility, C/Ilevels associated with respective UEs 1220, capabilities of backhaullinks between respective cells, or the like. By way of example,cooperation type selector 1214 can select CS and/or another similarsimple form of cell cooperation in the case of high-mobility UEs and/orrapidly changing channel conditions associated with a given UE 1220.Additionally or alternatively, if mobility of a given UE 1220 isdetermined to be low, or a high degree of antenna correlation is presentwith respect to the UE 1220, more advanced cooperation techniques suchas JT via inter-cell packet sharing (e.g., in the case of a relativelyslow backhaul link between cells 1210) or CBF (e.g., in the case of arelatively fast backhaul link between cells 1210) can be selected. Inanother example, utility computation module 1212 and/or cooperationstrategy selector 1214 can operate based at least in part on informationobtained from respective UEs 1220 (e.g., via a feedback module 1222 atthe respective UEs 1220).

In accordance with one aspect, a projected rate associated withrespective UEs 1220 can be calculated (e.g., by utility computationmodule 1212) and leveraged with factors such as backhaul bandwidth,latency constraints, or the like, to select between respectivecooperation techniques. For example, cooperation type selector 1212 canrule out a JT technique using backhaul bandwidth and latency uncertaintybased on associated a priori and/or long-term backhaul linkclassifications. In another example, channel state information at thetransmitter (CSIT) delivery delay and accuracy, as well as schedulingdelay and/or other suitable factors, can be factored in projected ratecalculation.

By way of specific example, cooperation type selector 1214 can utilize aset of cooperation technique selection rules as follows. First,cooperation type selector 1214 can rule out a JT technique based on along-term backhaul link classification. Further, cooperation typeselector 1214 can consider CBF techniques over JT in the event that aratio of a combined energy C/I to the best node C/I is below apredefined threshold. In addition, if an associated channel predictionerror is above a threshold value, cooperation type selector 1214 canconsider CS (e.g., in the event that CBF and/or JT are possible).

In accordance with another aspect, utility computation module 1212 cancompute per-UE projected rates based on various factors. These factorscan include, for example, propagation channels for respective linksinvolved in a utilized cooperation strategy (e.g., taking into accountpower and bandwidth resources allocated per link); channel predictionaccuracy based on projected downlink estimation error at respective UEs1220 and corresponding feedback delay; anticipated interference levelsfrom cooperative and non-cooperative network nodes (e.g., cells 1210and/or UEs 1220), taking into account spatial interference structures asapplicable; and/or any other suitable factors. In one example,respective UEs 1220 in system 1200 can provide information relating todownlink estimation errors, feedback delay, UE processing loss,interference nulling capability, and/or other information relating tothe operational capabilities of the respective UEs 1220 to respectivecells 1210 via feedback module 1222 and/or any other suitable means.

In one example, utility computation module 1212 can perform utilitycomputations for a given UE 1220 based on various requirements forchannel state information at the transmitter (CSIT). CSIT requirementscan vary, for example, based on a cooperation strategy employed byrespective cells 1210 with respect to a given UE 1220. By way ofspecific example, it can be appreciated that CSIT requirementsassociated with iterative signal processing and/or CBF can differsubstantially between CSIT requirements for CS. In one example, a cell1210 can utilize an assumption of accurate CSIT at moderate to highpost-processing carrier to interference (CA) levels in order to employfirst order approximation of an associated CSIT effect. Additionally oralternatively, in the event that a substantially high error effect(e.g., due to spatial error) is encountered, CS can be favored by cell1210 over more complex signal processing techniques. In accordance withone aspect, a threshold at which CS is selected over such techniques canbe based on an empirical measure of channel prediction, as described infurther detail herein.

In accordance with a further aspect, cooperation strategy selector 1214can utilize one or more strategy utility maximization techniques foroptimizing a cooperation strategy to be utilized with respect torespective UEs 1220. For example, one or more iterative utilitymaximization algorithms (e.g., algorithms similar to iterative pricing)can be utilized, wherein an iterative search is performed at respectivenetwork nodes (e.g., cells 1210, sectors within cells 1210, etc.) forrespective candidate cooperation strategies. In one example, variouscooperation technique constraints can be considered, which can be, forexample, reflected in constraints on the beam coefficients of variousnodes. In another example, first order extension can be utilized toupdate respective beam weights at respective iterations untilconvergence. In various implementations, convergence can be madedependent on an algorithm starting point, which can be selected in avariety of manners. For example, a starting point can be selected viazero-forcing (ZF) across respective cooperating nodes, maximum ratiocombining (MRC) and/or MMSE-based approaches, or the like. In oneexample, power allocation techniques can be applied in addition to ZFand/or MRC.

Referring next to FIG. 13, an example system 1300 that facilitatescoordinated multipoint communication in accordance with various aspectsdescribed herein is illustrated. As FIG. 13 illustrates, system 1300 caninclude respective user devices 1330 that can communicate with one ormore associated network cells, such as serving cell(s) 1310 andauxiliary cell(s) 1320. It should be appreciated, however, that nofunctionality of cells 1310-1320 is intended to be implied by the namingof “serving cell(s)” 1310 and “auxiliary cell(s)” 1320. For example, itshould be appreciated that an auxiliary cell 1320 can serve a userdevice 1330 by providing communication coverage for user device 1330 inaddition to, or in place of, a serving cell 1310 in some cases.

In accordance with one aspect, respective serving cells 1310 andauxiliary cells 1320 can cooperate to perform N-MIMO or CoMPcommunication with one or more user devices 1330. For example, varioustechniques can be utilized to facilitate cooperation between respectivecells 1310-1320, between respective sectors associated with one or morecells 1310-1320, and/or any other suitable network entities. Suchcooperation can be facilitated by, for example, a TX/RX coordinationmodule 1312 associated with respective cells 1310-1320 and/or any othersuitable mechanism(s). Further, TX/RX coordination module 1312 canfacilitate cooperation between respective network entities according toany suitable network cooperation strategy(ies), such as fractionalfrequency reuse, silencing, coordinated beamforming, joint transmission,or the like.

In one example, coordinated beamforming can be conducted between networknodes associated with respective cells 1310-1320 by coordinatingtransmissions from the respective cells 1310-1320 such that if atransmission to a user device 1330 occurs from a given cell 1310 or1320, a beam is chosen to serve the user device 1330 by the given cell1310 or 1320 such that the transmission to the user device 1330 isorthogonal or otherwise substantially mismatched to user devicesscheduled on neighboring cells 1310 and/or 1320. By doing so, it can beappreciated that beamforming gains can be realized for a desired userdevice 1330 while simultaneously reducing the effects of interference onneighboring network devices. In one example, coordinated beamforming canbe facilitated by performing scheduling, beam selection, user selection(e.g., by selecting user devices 1330 having desirable beams thatsubstantially limit interference at neighboring devices), or the like.

Additionally or alternatively, joint transmission can be conductedbetween a plurality of network nodes and a given user device 1330 by,for example, pooling resources designated for transmission to a givenuser device 1330 and transmitting the pooled resources via multipledistinct network nodes (e.g., nodes corresponding to a serving cell 1310as well as an auxiliary cell 1320). For example, instead of a first celltransmitting a modulation symbol x to a first user and a second celltransmitting a modulation symbol y to a second user, the cells cancooperate such that the first cell transmits ax+by to one or both of theusers and the second cell transmits cx+dy to the same user(s), where a,b, c, and d are coefficients chosen to optimize the signal-to-noiseratio (SNR) of the users, system capacity, and/or any other suitablemetric(s). In one example, resource pooling among network nodescorresponding to different cells 1310-1320 can be conducted via abackhaul link between the cells 1310-1320 and/or any other suitablemechanism. In another example, similar techniques can be utilized foruplink joint transmission, wherein a user device 1330 can be configuredto transmit data, control signaling, and/or other appropriateinformation to multiple network nodes.

In accordance with one aspect, various aspects of uplink and downlinkCoMP communication can be based on feedback provided by respective userdevices 1330. For example, a N-MIMO feedback module 1332 at respectiveuser devices 1330 can be utilized to provide feedback to various cells1310-1320, which in turn can utilize a user feedback processing module1314 and/or other suitable means to utilize the feedback in conductingcooperative communication within system 1300. By way of example, in thecase of downlink CoMP communication, a N-MIMO feedback module 1332 atuser device(s) 1330 can facilitate channel reporting to respective cells1310-1320 of respective serving cells as well as one or more neighboringnon-cooperative cells. By way of another example, in the case of uplinkCoMP communication, N-MIMO feedback module 1332 can provide feedbackinformation to respective cells 1310-1320 in combination withrespectively scheduled uplink transmissions to the cells 1310-1320 thatcan be utilized by the cells 1310-1320 to facilitate the removal ofinterference from the corresponding uplink transmissions.

Turning to FIG. 14, an exemplary wireless communication system 1400 isillustrated. In one example, system 1400 can be configured to support anumber of users, in which various disclosed embodiments and aspects canbe implemented. As shown in FIG. 14, by way of example, system 1400 canprovide communication for multiple cells 1402, (e.g., macro cells 1402a-1402 g), with respective cells being serviced by corresponding accesspoints (AP) 1404 (e.g., APs 1404 a-1404 g). In one example, one or morecells can be further divided into respective sectors (not shown).

As FIG. 14 further illustrates, various access terminals (ATs) 1406,including ATs 1406 a-1406 k, can be dispersed throughout system 1400. Inone example, an AT 1406 can communicate with one or more APs 1404 on aforward link (FL) and/or a reverse link (RL) at a given moment,depending upon whether the AT is active and whether it is in softhandoff and/or another similar state. As used herein and generally inthe art, an AT 1406 can also be referred to as a user equipment (UE), amobile terminal, and/or any other suitable nomenclature. In accordancewith one aspect, system 1400 can provide service over a substantiallylarge geographic region. For example, macro cells 1402 a-1402 g canprovide coverage for a plurality of blocks in a neighborhood and/oranother similarly suitable coverage area.

Referring now to FIG. 15, a block diagram illustrating an examplewireless communication system 1500 in which various aspects describedherein can function is provided. In one example, system 1500 is amultiple-input multiple-output (MIMO) system that includes a transmittersystem 1510 and a receiver system 1550. It should be appreciated,however, that transmitter system 1510 and/or receiver system 1550 couldalso be applied to a multi-input single-output system wherein, forexample, multiple transmit antennas (e.g., on a base station), cantransmit one or more symbol streams to a single antenna device (e.g., amobile station). Additionally, it should be appreciated that aspects oftransmitter system 1510 and/or receiver system 1550 described hereincould be utilized in connection with a single output to single inputantenna system.

In accordance with one aspect, traffic data for a number of data streamsare provided at transmitter system 1510 from a data source 1512 to atransmit (TX) data processor 1514. In one example, each data stream canthen be transmitted via a respective transmit antenna 1524.Additionally, TX data processor 1514 can format, encode, and interleavetraffic data for each data stream based on a particular coding schemeselected for each respective data stream in order to provide coded data.In one example, the coded data for each data stream can then bemultiplexed with pilot data using OFDM techniques. The pilot data canbe, for example, a known data pattern that is processed in a knownmanner. Further, the pilot data can be used at receiver system 1550 toestimate channel response. Back at transmitter system 1510, themultiplexed pilot and coded data for each data stream can be modulated(i.e., symbol mapped) based on a particular modulation scheme (e.g.,BPSK, QSPK, M-PSK, or M-QAM) selected for each respective data stream inorder to provide modulation symbols. In one example, data rate, coding,and modulation for each data stream can be determined by instructionsperformed on and/or provided by processor 1530.

Next, modulation symbols for all data streams can be provided to a TXprocessor 1520, which can further process the modulation symbols (e.g.,for OFDM). TX MIMO processor 1520 can then provides N_(T) modulationsymbol streams to N_(T) transceivers 1522 a through 1522 t. In oneexample, each transceiver 1522 can receive and process a respectivesymbol stream to provide one or more analog signals. Each transceiver1522 can then further condition (e.g., amplify, filter, and upconvert)the analog signals to provide a modulated signal suitable fortransmission over a MIMO channel. Accordingly, N_(T) modulated signalsfrom transceivers 1522 a through 1522 t can then be transmitted fromN_(T) antennas 1524 a through 1524 t, respectively.

In accordance with another aspect, the transmitted modulated signals canbe received at receiver system 1550 by N_(R) antennas 1552 a through1552 r. The received signal from each antenna 1552 can then be providedto respective transceivers 1554. In one example, each transceiver 1554can condition (e.g., filter, amplify, and downconvert) a respectivereceived signal, digitize the conditioned signal to provide samples, andthen processes the samples to provide a corresponding “received” symbolstream. An RX MIMO/data processor 1560 can then receive and process theN_(R) received symbol streams from N_(R) transceivers 1554 based on aparticular receiver processing technique to provide N_(T) “detected”symbol streams. In one example, each detected symbol stream can includesymbols that are estimates of the modulation symbols transmitted for thecorresponding data stream. RX processor 1560 can then process eachsymbol stream at least in part by demodulating, deinterleaving, anddecoding each detected symbol stream to recover traffic data for acorresponding data stream. Thus, the processing by RX processor 1560 canbe complementary to that performed by TX MIMO processor 1520 and TX dataprocessor 1516 at transmitter system 1510. RX processor 1560 canadditionally provide processed symbol streams to a data sink 1564.

In accordance with one aspect, the channel response estimate generatedby RX processor 1560 can be used to perform space/time processing at thereceiver, adjust power levels, change modulation rates or schemes,and/or other appropriate actions. Additionally, RX processor 1560 canfurther estimate channel characteristics such as, for example,signal-to-noise-and-interference ratios (SNRs) of the detected symbolstreams. RX processor 1560 can then provide estimated channelcharacteristics to a processor 1570. In one example, RX processor 1560and/or processor 1570 can further derive an estimate of the “operating”SNR for the system. Processor 1570 can then provide channel stateinformation (CSI), which can comprise information regarding thecommunication link and/or the received data stream. This information caninclude, for example, the operating SNR. The CSI can then be processedby a TX data processor 1518, modulated by a modulator 1580, conditionedby transceivers 1554 a through 1554 r, and transmitted back totransmitter system 1510. In addition, a data source 1512 at receiversystem 1550 can provide additional data to be processed by TX dataprocessor 1518.

Back at transmitter system 1510, the modulated signals from receiversystem 1550 can then be received by antennas 1524, conditioned bytransceivers 1522, demodulated by a demodulator 1540, and processed by aRX data processor 1542 to recover the CSI reported by receiver system1550. In one example, the reported CSI can then be provided to processor1530 and used to determine data rates as well as coding and modulationschemes to be used for one or more data streams. The determined codingand modulation schemes can then be provided to transceivers 1522 forquantization and/or use in later transmissions to receiver system 1550.Additionally and/or alternatively, the reported CSI can be used byprocessor 1530 to generate various controls for TX data processor 1514and TX MIMO processor 1520. In another example, CSI and/or otherinformation processed by RX data processor 1542 can be provided to adata sink 1544.

In one example, processor 1530 at transmitter system 1510 and processor1570 at receiver system 1550 direct operation at their respectivesystems. Additionally, memory 1532 at transmitter system 1510 and memory1572 at receiver system 1550 can provide storage for program codes anddata used by processors 1530 and 1570, respectively. Further, atreceiver system 1550, various processing techniques can be used toprocess the N_(R) received signals to detect the N_(T) transmittedsymbol streams. These receiver processing techniques can include spatialand space-time receiver processing techniques, which can also bereferred to as equalization techniques, and/or “successivenulling/equalization and interference cancellation” receiver processingtechniques, which can also be referred to as “successive interferencecancellation” or “successive cancellation” receiver processingtechniques.

FIG. 16 illustrates an example communication system 1600 that enablesdeployment of access point base stations within a network environment.As shown in FIG. 16, system 1600 can include multiple access point basestations (e.g., femto cells or Home Node B units (HNBs)) such as, forexample, HNBs 1610. In one example, respective HNBs 1610 can beinstalled in a corresponding small scale network environment, such as,for example, one or more user residences 1630. Further, respective HNBs1610 can be configured to serve associated and/or alien UE(s) 1620. Inaccordance with one aspect, respective HNBs 1610 can be coupled to theInternet 1640 and a mobile operator core network 1650 via a DSL router,a cable modem, and/or another suitable device (not shown). In accordancewith one aspect, an owner of a femto cell or HNB 1610 can subscribe tomobile service, such as, for example, 3G/4G mobile service, offeredthrough mobile operator core network 1650. Accordingly, UE 1620 can beenabled to operate both in a macro cellular environment 1660 and in aresidential small scale network environment.

In one example, UE 1620 can be served by a set of Femto cells or HNBs1610 (e.g., HNBs 1610 that reside within a corresponding user residence1630) in addition to a macro cell mobile network 1660. As used hereinand generally in the art, a home femto cell is a base station on whichan AT or UE is authorized to operate on, a guest femto cell refers to abase station on which an AT or UE is temporarily authorized to operateon, and an alien femto cell is a base station on which the AT or UE isnot authorized to operate on. In accordance with one aspect, a femtocell or HNB 1610 can be deployed on a single frequency or on multiplefrequencies, which may overlap with respective macro cell frequencies.

It is to be understood that the aspects described herein can beimplemented by hardware, software, firmware, middleware, microcode, orany combination thereof. When the systems and/or methods are implementedin software, firmware, middleware or microcode, program code or codesegments, they can be stored in a machine-readable medium, such as astorage component. A code segment can represent a procedure, a function,a subprogram, a program, a routine, a subroutine, a module, a softwarepackage, a class, or any combination of instructions, data structures,or program statements. A code segment can be coupled to another codesegment or a hardware circuit by passing and/or receiving information,data, arguments, parameters, or memory contents. Information, arguments,parameters, data, etc. can be passed, forwarded, or transmitted usingany suitable means including memory sharing, message passing, tokenpassing, network transmission, etc.

For a software implementation, the techniques described herein can beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. The software codes can be storedin memory units and executed by processors. The memory unit can beimplemented within the processor or external to the processor, in whichcase it can be communicatively coupled to the processor via variousmeans as is known in the art.

What has been described above includes examples of one or more aspects.It is, of course, not possible to describe every conceivable combinationof components or methodologies for purposes of describing theaforementioned aspects, but one of ordinary skill in the art canrecognize that many further combinations and permutations of variousaspects are possible. Accordingly, the described aspects are intended toembrace all such alterations, modifications and variations that fallwithin the spirit and scope of the appended claims. Furthermore, to theextent that the term “includes” is used in either the detaileddescription or the claims, such term is intended to be inclusive in amanner similar to the term “comprising” as “comprising” is interpretedwhen employed as a transitional word in a claim. Furthermore, the term“or” as used in either the detailed description or the claims is meantto be a “non-exclusive or.”

What is claimed is:
 1. A method comprising: determining an interferencereporting schedule for a user equipment in relation to a serving set ofnetwork cells; scheduling null pilot intervals for the serving set ofnetwork cells based on the interference reporting schedule, wherein thescheduled null pilot intervals comprise at least one null pilot intervalassociated with limited transmission by a plurality of network cells ofthe serving set of network cells; conducting the limited transmissionduring the at least one null pilot interval, the limited transmissioncomprising one of silencing transmission during the at least one nullpilot interval or reducing transmit power by a power backoff valueduring the at least one null pilot interval; receiving a combinedinterference report from the user equipment comprising an indication ofchannel conditions measured by the user equipment during the at leastone null pilot interval, wherein the measured channel conditionscomprise interference associated with one or more network cells notwithin the plurality of network cells; and scheduling a communication byone or more network cells of the serving set of network cells to theuser equipment based at least in part on the received combinedinterference report.
 2. The method of claim 1, further comprisingselecting a transmission scheme for the communication to the userequipment, wherein the selected transmission scheme comprises one ormore of joint transmission, coordinated silencing, or coordinatedbeamforming.
 3. The method of claim 1, wherein the combined interferencereport comprises information relating to an achievable channel qualityfor the one or more network cells of the serving set of network cellsunder different coordination schemes.
 4. The method of claim 1, whereinthe combined interference report comprises information relating to afrequency bandwidth or to one or more frequency sub-bands of acorresponding communication system.
 5. The method of claim 1, whereinthe communication is further based on a mobility of the user equipmentor an antenna correlation of the user equipment.
 6. The method of claim1, further comprising: identifying a primary interfering network cellamong the network cells not within the plurality of network cells of theserving set of network cells; and determining a correlation of transmitantennas of the primary interfering network cell, wherein thecommunication is based at least in part on the determined correlation.7. The method of claim 1, wherein the combined interference reportcomprises channel information associated with downlink channels of theone or more network cells of the serving set of network cells, andwherein the scheduling of the communication is based at least in part onthe reported channel information associated with the downlink channels.8. The method of claim 1, wherein the combined interference reportcomprises an amount of received power associated with one or more ofreference signals or synchronization signals from the one or morenetwork cells not within the plurality of network cells of the servingset of network cells, and wherein the scheduling of the communication isbased at least in part on the reported amount of received power of theone or more of reference signals or synchronization signals.
 9. A methodcomprising: measuring, by a user equipment associated with a serving setof network cells, channel conditions during a null pilot intervalscheduled in accordance with an interference reporting schedule for theserving set of network cells, wherein a plurality of network cells ofthe serving set of network cells silence or reduce transmit power oftransmissions that occur during the scheduled null pilot interval;sending, to a network cell of the serving set of network cells, acombined interference report comprising an indication of the channelconditions measured by the user equipment during the at least one nullpilot interval, wherein the measured channel conditions compriseinterference associated with one or more network cells not within theplurality of network cells; and receiving communications from one ormore network cells of the serving set of network cells, wherein thereceived communications are based at least in part on the combinedinterference report.
 10. The method of claim 9, further comprising:determining an achievable channel quality associated with channelscorresponding to respective network cells in the serving set of networkcells; and providing the achievable channel quality with the combinedinterference report.
 11. The method of claim 9, wherein: the measuringcomprises identifying a primary interfering network cell; and thecombined interference report comprises an identity of the primaryinterfering network cell.
 12. The method of claim 9, further comprising:identifying one or more interfering network cells comprising a pluralityof transmit antennas, wherein the measuring comprises computing acorrelation between respective transmit antennas of the one or moreinterfering network cells.
 13. The method of claim 12, wherein the oneor more interfering network cells comprise a primary interfering networkcell.
 14. The method of claim 12, wherein the combined interferencereport comprises information relating to the computed correlationbetween the respective transmit antennas of the one or more interferingnetwork cells.
 15. The method of claim 12, further comprising:determining an amount of interference nulling for application relativeto the one or more interfering network cells based on the computedcorrelation between the respective transmit antennas of the one or moreinterfering network cells; and estimating a projected rate forcommunication based on application of the determined amount ofinterference nulling, wherein the combined interference report comprisesthe estimated projected rate.
 16. The method of claim 12, furthercomprising: determining an amount of receiver interference nulling forapplication relative to the one or more interfering network cells via aplurality of receive antennas, wherein the combined interference reportcomprises the determined amount of receiver interference nulling. 17.The method of claim 9, wherein the measuring comprises measuring anamount of received power associated with one or more of referencesignals or synchronization signals from the one or more network cellsnot within the plurality of network cells of the serving set of networkcells.
 18. The method of claim 9, wherein the measuring furthercomprises: identifying a loading indicator within at least one of areference signal or synchronization signal from a network cell notwithin the plurality of network cells of the serving set of networkcells; determining loading of the network cell based at least in part onthe loading indicator; and estimating interference caused by the networkcell as a function of loading of the network cell.
 19. The method ofclaim 18, wherein the identifying the loading indicator comprisesidentifying the loading indicator within a preamble of the referencesignal or the synchronization signal.
 20. The method of claim 9, whereinthe measuring comprises measuring an amount of received power associatedwith at least one of reference signaling, a primary synchronizationsignal (PSS), a secondary synchronization signal (SSS), or Low ReusePreamble (LRP) signaling communicated by the one or more network cellsnot within the plurality of network cells of the serving set of networkcells.
 21. A communications device comprising: at least one processorconfigured to: determine an interference reporting schedule for a userequipment in relation to a serving set of network cells; schedule nullpilot intervals for the serving set of network cells based on theinterference reporting schedule, wherein the scheduled null pilotintervals comprise at least one null pilot interval associated withlimited transmission by a plurality of network cells of the serving setof network cells; conduct the limited transmission during the at leastone null pilot interval, the limited transmission comprising one ofsilencing transmission during the at least one scheduled null pilotinterval or reducing transmit power by a power backoff value during theat least one null pilot interval; receive a combined interference reportfrom the user equipment comprising an indication of channel conditionsmeasured by the user equipment during the at least one null pilotinterval, wherein the measured channel conditions comprise interferenceassociated with one or more network cells not within the plurality ofnetwork cells; and schedule a communication by one or more network cellsof the serving set of network cells to the user equipment based at leastin part on the received combined interference report.
 22. Thecommunications device of claim 21, wherein the at least one processor isfurther configured to select a transmission scheme for the communicationto the user equipment, and wherein the selected transmission schemecomprises one or more of joint transmission, coordinated silencing, orcoordinated beamforming.
 23. The communications device of claim 21,wherein the combined interference report comprises information relatingto an achievable channel quality for the one or more network cells underone or more coordination schemes.
 24. The communications device of claim21, wherein the combined interference report comprises informationrelating to a frequency bandwidth or to one or more frequency sub-bandsof a corresponding communication system.
 25. The communications deviceof claim 21, wherein the communication is further based on a mobility ofthe user equipment or an antenna correlation of the user equipment. 26.The communications device of claim 21, wherein the at least oneprocessor is further configured to: identify a primary interferingnetwork cell among the network cells not within the plurality of networkcells of the serving set of network cells; and determine a correlationof transmit antennas of the primary interfering network cell; andschedule the communication based at least in part on the determinedcorrelation.
 27. The communications device of claim 21, wherein thecombined interference report comprises channel information associatedwith downlink channels of the one or more network cells of the servingset of network cells, and wherein the at least one processor is furtherconfigured to schedule the communication based at least in part on thereported channel information associated with the downlink channels. 28.The communications device of claim 21, wherein the combined interferencereport comprises an amount of received power associated with one or moreof reference signals or synchronization signals from the one or morenetwork cells not within the plurality of network cells of the servingset of network cells and wherein the at least one processor is furtherconfigured to schedule the communication based at least in part on thereported amount of received power of the one or more of referencesignals or synchronization signals.
 29. A communications devicecomprising: at least one processor configured to: measure, by a userequipment associated with a serving set of network cells, channelconditions during a null pilot interval scheduled in accordance with aninterference reporting schedule for the serving set of network cells,wherein a plurality of network cells of the serving set of network cellssilence or reduce transmit power of transmissions that occur during thescheduled null pilot interval; send, to a network cell of the servingset of network cells, a combined interference report comprising anindication of the channel conditions measured by the user equipmentduring the at least one null pilot interval, wherein the measuredchannel conditions comprise interference associated with one or morenetwork cells not within the plurality of network cells; and receivecommunications from one or more network cells of the serving set ofnetwork cells, wherein the received communications are based at least inpart on the combined interference report.
 30. The communications deviceof claim 29, wherein the at least one processor is further configuredto: determine an achievable channel quality associated with channelscorresponding to respective network cells in the serving set of networkcells; and provide the achievable channel quality with the combinedinterference report.
 31. The communications device of claim 29, whereinthe at least one processor is further configured to identify a primaryinterfering network cell, and wherein the combined interference reportcomprises an identity of the primary interfering network cell.
 32. Thecommunications device of claim 29, wherein the at least one processor isfurther configured to identify one or more interfering network cellscomprising a plurality of transmit antennas, and wherein the measuringcomprises computing a correlation between respective transmit antennasof the one or more interfering network cells.
 33. The communicationsdevice of claim 32, wherein the one or more interfering network cellscomprise a primary interfering network cell.
 34. The communicationsdevice of claim 32, wherein the combined interference report comprisesinformation relating to the computed correlation between the respectivetransmit antennas of the one or more interfering network cells.
 35. Thecommunications device of claim 32, wherein the at least one processor isfurther configured to: determine an amount of interference nulling forapplication relative to the one or more interfering network cells basedon the computed correlation between the respective transmit antennas ofthe one or more interfering network cells; estimate a projected rate forcommunication based on application of the determined amount ofinterference nulling; and send, with the combined interference report,the estimated projected rate.
 36. The communications device of claim 32,wherein the at least one processor is further configured to determine anamount of receiver interference nulling for application relative to theone or more interfering network cells via a plurality of receiveantennas, and send, with the combined interference report, thedetermined amount of receiver interference nulling.
 37. Thecommunications device of claim 29, wherein the at least one processor isfurther configured to measure an amount of received power associatedwith one or more of reference signals or synchronization signals fromthe one or more network cells not within the plurality of network cellsof the serving set of network cells.
 38. The communications device ofclaim 29, wherein the at least one processor is further configured to:identify a loading indicator within at least one of a reference signalor synchronization signal from a network cell not within the pluralityof network cells of the serving set of network cells; determine loadingof the network cell based at least in part on the loading indicator; andestimate interference caused by the network cell as a function ofloading of the network cell.
 39. The communications device of claim 38,wherein the at least one processor is further configured to identify theloading indicator within a preamble of the reference signal or thesynchronization signal.
 40. The communications device of claim 29,wherein the at least one processor is further configured to measure anamount of received power associated with at least one of referencesignaling, a primary synchronization signal (PSS), a secondarysynchronization signal (SSS), or Low Reuse Preamble (LRP) signalingcommunicated by the one or more network cells not within the pluralityof network cells of the serving set of network cells.
 41. Acommunications device comprising: means for determining an interferencereporting schedule for a user equipment in relation to a serving set ofnetwork cells; means for scheduling null pilot intervals for the servingset of network cells based on the interference reporting schedule,wherein the scheduled null pilot intervals comprise at least one nullpilot interval associated with limited transmission by a plurality ofnetwork cells of the serving set of network cells; means for conductingthe limited transmission during the at least one null pilot interval,the limited transmission comprising one of silencing transmission duringthe at least one null pilot interval or reducing transmit power by apower backoff value during the at least one null pilot interval; meansfor receiving a combined interference report from the user equipmentcomprising an indication of channel conditions measured by the userequipment during the at least one null pilot interval, wherein themeasured channel conditions comprise interference associated with one ormore network cells not within the plurality of network cells; and meansfor scheduling a communication by one or more network cells of theserving set of network cells to the user equipment based at least inpart on the received combined interference report.
 42. Thecommunications device of claim 41, wherein the means for scheduling thecommunication identifies a primary interfering network cell among thenetwork cells not within the plurality of network cells of the set ofnetwork cells, determines a correlation of transmit antennas of theprimary interfering network cell, and schedules the communication basedat least in part on the determined correlation.
 43. The communicationsdevice of claim 41, wherein the combined interference report compriseschannel information associated with downlink channels of the one or morenetwork cells of the serving set of network cells, and wherein the meansfor scheduling the communication schedules the communication based atleast in part on the reported channel information associated with thedownlink channels.
 44. A communications device comprising: means formeasuring, by a user equipment associated with a serving set of networkcells, channel conditions during a null pilot interval scheduled inaccordance with an interference reporting schedule for the serving setof network cells, wherein a plurality of network cells of the servingset of network cells silence or reduce transmit power of transmissionsthat occur during the scheduled null pilot interval; means for sending,to a network cell of the serving set of network cells, a combinedinterference report comprising an indication of the channel conditionsmeasured by the user equipment during the at least one null pilotinterval, wherein the measured channel conditions comprise interferenceassociated with one or more network cells not within the plurality ofnetwork cells; and means for receiving communications from one or morenetwork cells of the serving set of network cells, wherein the receivedcommunications are based at least in part on the combined interferencereport.
 45. The communications device of claim 44, wherein the means formeasuring determines an achievable channel quality associated withchannels corresponding to respective network cells in the serving set ofnetwork cells and the means for sending the combined interference reportprovides the achievable channel quality with the combined interferencereport.
 46. The communications device of claim 44, wherein the means formeasuring identifies one or more interfering network cells comprising aplurality of transmit antennas and computes a correlation betweenrespective transmit antennas of the one or more interfering networkcells.
 47. The communications device of claim 46, wherein the combinedinterference report comprises information relating to the computedcorrelation between the respective transmit antennas of the one or moreinterfering network cells.
 48. The communications device of claim 46,wherein the means for measuring determines an amount of interferencenulling for application relative to the one or more interfering networkcells based on the computed correlation between the respective transmitantennas of the one or more interfering network cells and estimates aprojected rate for communication based on application of the determinedamount of interference nulling, and wherein the combined interferencereport comprises the estimated projected rate.
 49. The communicationsdevice of claim 46, wherein the means for measuring determines an amountof receiver interference nulling for application relative to the one ormore interfering network cells via a plurality of receive antennas, andwherein the combined interference report comprises the determined amountof receiver interference nulling.
 50. A non-transitory computer-readablemedium storing computer-executable code, comprising: code fordetermining an interference reporting schedule for a user equipment inrelation to a serving set of network cells; code for scheduling nullpilot intervals for the serving set of network cells based on theinterference reporting schedule, wherein the scheduled null pilotintervals comprise at least one null pilot interval associated withlimited transmission by a plurality of network cells of the serving setof network cells; code for conducting the limited transmission duringthe at least one null pilot interval, the limited transmissioncomprising one of silencing transmission during the at least one nullpilot interval or reducing transmit power by a power backoff valueduring the at least one null pilot interval; code for receiving acombined interference report from the user equipment comprising anindication of channel conditions measured by the user equipment duringthe at least one null pilot interval, wherein the measured channelconditions comprise interference associated with one or more networkcells not within the plurality of network cells; and code for schedulinga communication by one or more network cells of the serving set ofnetwork cells to the user equipment based at least in part on thereceived combined interference report.
 51. The non-transitorycomputer-readable medium of claim 50, wherein the non-transitorycomputer-readable medium further comprises: code for identifying aprimary interfering network cell among the network cells not within theplurality of network cells of the serving set of network cells; code fordetermining a correlation of transmit antennas of the primaryinterfering network cell; and code for scheduling the communicationbased at least in part on the determined correlation.
 52. Thenon-transitory computer-readable medium of claim 50, wherein thecombined interference report comprises channel information associatedwith downlink channels of the one or more network cells of the servingset of network cells, and wherein the scheduling the communication isbased at least in part on the reported channel information associatedwith the downlink channels.
 53. A non-transitory computer-readablemedium storing computer-executable code, comprising: code for measuring,by a user equipment associated with a serving set of network cells,channel conditions during a null pilot interval scheduled in accordancewith an interference reporting schedule for the serving set of networkcells, wherein a plurality of network cells of the serving set ofnetwork cells silence or reduce transmit power of transmissions thatoccur during the scheduled null pilot interval; code for sending, to anetwork cell of the serving set of network cells, a combinedinterference report comprising an indication of the channel conditionsmeasured by the user equipment during the at least one null pilotinterval, wherein the measured channel conditions comprise interferenceassociated with one or more network cells not within the plurality ofnetwork cells; and code for receiving communications from one or morenetwork cells of the serving set of network cells, wherein the receivedcommunications are based at least in part on the combined interferencereport.
 54. The non-transitory computer-readable medium of claim 53,wherein the non-transitory computer-readable medium further comprises:code for determining an achievable channel quality associated withchannels corresponding to respective network cells in the serving set ofnetwork cells; and code for providing the achievable channel qualitywith the combined interference report.
 55. The non-transitorycomputer-readable medium of claim 53, wherein the non-transitorycomputer-readable medium further comprises code for identifying aprimary interfering network cell, and wherein the combined interferencereport comprises an identity of the primary interfering network cell.56. The non-transitory computer-readable medium of claim 53, wherein thenon-transitory computer-readable medium further comprises: code foridentifying one or more interfering network cells comprising a pluralityof transmit antennas; and code for computing a correlation betweenrespective transmit antennas of the one or more interfering networkcells.
 57. The method of claim 9, further comprising: measuring channelconditions corresponding to network cells in the serving set of networkcells; and providing information corresponding to the measured channelconditions associated with the network cells in the serving set ofnetwork cells with the combined interference report.
 58. Thecommunications device of claim 29, wherein the at least one processor isfurther configured to: measure channel conditions corresponding tonetwork cells in the serving set of network cells; and provideinformation corresponding to the measured channel conditions associatedwith the network cells in the serving set of network cells with thecombined interference report.
 59. The communications device of claim 44,wherein: the means for measuring measures channel conditionscorresponding to network cells in the serving set of network cells; andthe means for sending provides information corresponding to the measuredchannel conditions associated with the network cells in the serving setof network cells with the combined interference report.
 60. Thenon-transitory computer-readable medium of claim 53, wherein thenon-transitory computer-readable medium further comprises: code formeasuring channel conditions corresponding to network cells in theserving set of network cells; and code for providing informationcorresponding to the measured channel conditions associated with thenetwork cells in the serving set of network cells with the combinedinterference report.
 61. The method of claim 10, wherein the providedachievable channel quality for the respective network cells in theserving set of network cells relates to at least one coordination schemeutilizing the one or more network cells of the serving set of networkcells.
 62. The method of claim 61, wherein the at least one coordinationscheme comprises one or more of coordinated silencing, coordinatedbeamforming, or joint transmission.